Previous research indicates that processes which regulate schistosome development and reproduction may be susceptible to steroids or compounds that are known to interfere with steroid metabolism in other animals. The proposed research will quantify and characterize, by gas chromatography mass-spectrometry, the steroids within immature and mature schistosomes, as well as the parasite's environment (i.e., host blood). This will be followed by an examination of the metabolic pathways utilized by the schistosome for the metabolism of its steroids. This will be accomplished by incubating parasites in radioactive steroids followed by characterization of labeled metabolites by HPLC. Work on steroid metabolism will be accompanied by a study of the physiological significance of schistosome steroids on basic metabolic processes (lipid, RNA, DNA, and protein synthesis) of the parasite and on processes regulatng maturation and reproductive fecundity and viability. Finally, exogenous steroids and compounds will be selected, based on their ability to inhibit schistosome steroid metabolic pathways, to determine if they are effective inhibitors of schistosome reproductive and/or developmental processes. Results from the proposed experiments should provide a biochemical basis for the physiological role that steroids play in regulating schistosome growth and reproduction. Information about steroids and/or the pathways involved in their metabolism should help in selected drugs (other steroids or non-steroids) that will interfere with the schistosome's growth and development. Once these drugs have been identified work can proceed to determine their value in controlling schistosomiasis.